EPHRATA, Wash. — The Columbia Basin pygmy rabbit is finally back in its old stomping grounds, munching olive-drab sagebrush and hopefully doing what rabbits do best.

Twenty of the creatures — each not much bigger than a man’s hand — were set free Tuesday in a remote wildlife reserve, an attempt to jump-start their population in central Washington state.

The rabbits were born and raised at Washington State University and at the Portland Zoo in Oregon. They are descendants of the last known wild rabbits, caught in 2002.

The captive breeding program that is helping the rabbits is similar to the effort that brought back the California condor, said Ren Lohoefener, Pacific regional director of the U.S. Fish and Wildlife Service.

“Any time you can bring something back from zero and re-establish it, it’s cause to celebrate,” he said. “This may be harder to do than with condors, because a lot more things eat bunnies than condors.”

The Columbia Basin pygmy rabbit is the country’s smallest native rabbit and the only one in the United States to dig its own burrows. The rabbit was listed for protection under the federal Endangered Species Act in 2003.

The reasons the Columbia Basin rabbits declined are not precisely known, although scientists suspect inbreeding among such a small population was a major factor. Range fires, farming, disease and predators also are thought to have taken their toll.

Pygmy rabbits are still found in the West’s Great Basin, but the isolated Columbia Basin group is considered to be an evolutionary distinct population, said Rod Sayler, a Washington State University associate professor of natural resource sciences who leads the captive breeding project.

Only three purebred descendants of the original wild rabbits remain at the captive breeding sites. The Columbia Basin rabbits were mated with more genetically diverse Idaho pygmy rabbits and their offspring carry at least 75 percent of the Columbia pygmy bloodlines. The crossbred rabbits became better breeders and more of their young survived.

“That population had been isolated for thousands of years,” Sayler said. “We added just enough to help them along and reproduction picked back up.”

The rabbits were released in the Sagebrush Flats area about 18 miles northwest of Ephrata, part of a five-county range that was the rabbits’ original habitat.

The dozen males and eight females were placed in artificial burrows made of 20-foot-long perforated plastic irrigation pipes until they get used to the place and dig their own. Each wore a tiny radio transmitter the size of a watch battery to help scientists track its movements.

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